The principal objective of this project is to continue the investigations already begun in this laboratory of the hormone prolactin. These include its measurement, regulation, state in circulating blood, biologic actions, and role in a number of disease processes - specifically cancer of the breast, pituitary tumors, cancer of the prostate, and various endocrine and central nervous system disorders. Associated objectives of this project, more or less closely related to the study of prolactin, are continuing investigations of other pituitary and hypothalamic hormones. These include primarily growth hormone and vasopressin. A specific study involving the posterior pituitary is proposed in this application as well as studies of somatostatin and other hypothalamic peptides. Overall, this project continues to aim at a general investigation of pituitary function and disease.